First of all, a related art service flow generation procedure in a wireless communication system will be described. The service flow generation may start from a base station or may start from a user equipment.
FIG. 1(a) illustrates a case when a service flow generation starts from a base station, and FIG. 1(b) illustrates a case when a service flow generation starts from a user equipment.
As shown in FIG. 1(a), in case the service flow generation starts from the base station, when the base station transmits a dynamic service addition request (hereinafter referred to as “DSA-REQ”) message to the user equipment, the user equipment transmits a dynamic service addition response (hereinafter referred to as “DSA-RSP”) message to the base station. Thereafter, the base station transmits a dynamic service addition acknowledgement (hereinafter referred to as “DSA-ACK”) message to the user equipment. At this point, the DSA-REQ includes a service flow ID and a QoS (Quality of Service) parameter set with respect to an uplink or downlink service flow.
As shown in FIG. 1(b), in case the service flow generation starts from the user equipment, when the user equipment transmits a DSA-REQ message to the base station, the base station transmits a DSA-RSP message to the user equipment. Thereafter, the user equipment transmits a DSA-ACK message to the base station. At this point, the DSA-REQ includes a QoS parameter set.
Additionally, the user equipment or the base station may change the QoS parameter set of the service flow through a dynamic service change request (hereinafter referred to as “DSC-REQ”) message and a dynamic service change response (hereinafter referred to as “DSC-RSP”) message.
A QoS parameter set associated with uplink data will now be described.
Table 1 shows QoS parameter sets when the uplink data correspond to Real-time constant bit-rate data streams, such as a UGS (Unsolicited Grant Service).
TABLE 1ParameterMeaningTolerated JiterAs in 11. 13.13If (Fixed length SDU){SDU sizeAs in 11. 13.16}Minimum reserved traffic rateAs in 11. 13.8Maximum LatencyAs in 11. 13.14Request/Transmission PolicyAs in 11. 13.12If(UL service flow) {Grant Scheduling TypeUGS as specified in 6.3.5.2.1Unsolicited Grant IntervalAs in 11. 13.20}
Table 2 shows QoS parameter sets when the uplink data correspond to Real-time semi-variable bit-rate data streams, such as an ertPS (extended real-time Polling Service).
TABLE 2ParameterMeaningMaximum LatencyAs specified in 11. 13.14Tolerated JiterAs specified in 11. 13.13Minimum reserved traffic rateAs specified in 11. 13.8Maximum Sustained traffic rateAs specified in 11. 13.6Traffic PriorityAs specified in 11. 13.5Request/Transmission PolicyAs specified in 11. 13.12Unsolicited IntervalAs specified in 11. 13.20
In Table 1 and Table 2, the Unsolicited Grant Interval field indicates an interval between continuous resource grant (or allocation) for the service flow. Such granted (or allocated) resource is used for data transmission.
Table 3 shows QoS parameter sets when the uplink data correspond to Real-time variable bit-rate data streams.
TABLE 3ParameterMeaningMaximum LatencyAs in 11. 13.14Minimum Reserved traffic rateAs in 11. 13.8Maximum Sustained traffic rateAs in 11. 13.6Traffic PriorityAs in 11. 13.5Request/Transmission PolicyAs in 11. 13.12If(UL service flow) {Scheduling TypertPS as in 6.3.5.2.2Unsolicited Scheduling IntervalAs in 11. 13.21}
In Table 3, the Unsolicited polling interval field indicates a maximum interval between resource grant (or allocation) for the service flow. Such granted (or allocated) resource is used for uplink resource request transmission.
Table 4 shows QoS parameter sets when the uplink data correspond to Delay-tolerant variable bit-rate data streams.
TABLE 4ParameterMeaningMinimum Reserved traffic rateAs in 11. 13.8Maximum Sustained traffic rateAs in 11. 13.16Traffic PriorityAs in 11. 13.5cAs in 11. 13.12If(UL service flow) {Scheduling TypenrtPS as in 6.3.5.2.3}
Table 5 shows QoS parameter sets when the uplink data correspond to BE (best effort) data streams.
TABLE 5ParameterMeaningMaximum Sustained traffic rateOptional. As in 11.13.8Maximum Sustained traffic rateAs in 11. 13.12If(UL service flow) {Scheduling TypeBE as in 6.3.5.2.4}
As shown in Table 1 to Table 5, the QoS parameter set included in the DSA-REQ does not include information on a resource grant starting point. More specifically, only the information on resource grant intervals exists, and the information on a point where the user equipment starts to request a resource grant and a point where the base station starts to allow the resource grant does not exist. Therefore, according to the related art, after a service flow is generated or corrected, the user equipment waits until the base station allocates (or grants) resource or performs a contention based resource grant request. Accordingly, during this process, a packet transmission delay and a packet loss may occur.